The disclosed invention relates to the field of high density information recording structures, and in particular to protection of the fragile recording surface of a disk-shaped information recording structure.
In high density information recording devices, information is recorded on a sensitive recording surface. The information is recorded on and read from the disk surface as the disk rotates at a high speed under either a magnetic or an optical head. In both high density recording devices, the extremely sensitive surface of both necessitate rigorous protection of the recording surface. In general, magnetic disks are coated with an ultra-thin, magnetically sensitive oxide layer. This layer is very susceptive to physical damage, as well as contamination from even the most minute of dust particles. Optical recording disks are coated with thin, light sensitive layers which react to exposure to high intensity light in order to create data marks. Optical disk recording surfaces are also extremly fragile and susceptible to physical damage.
In the early magnetic recording devices, the information recording disks were an integral, fixed, part of the storage device. However, in such a device having non-removable disks, the amount of information which can be stored in a given device is limited to the total storage capacity of the disks. To address this problem, in magnetic recording, devices using interchangeable media have been developed. However, when using interchangeable disks, particular care had to be taken to prevent physical damage and contamination of the disk when not loaded in the recording device. To provide this necessary protection, rigid and hermetically sealed magnetic disk packs have been provided. These disk packs usually include a spindle having the plurality of disks mounted thereto, a plurality of magnetic read/write heads, and an actuator system, which radially moves the magnetic heads over the disk surface. In some magnetic recording devices, as many as eight permanently mounted disks have been placed upon a single spindle. Some disk packs even included two separate spindles, along with the associated hardware.
However, a severe deterrent to the use of such disk packs is the expense of including a complete set of spindles and actuators in each disk pack. A much cheaper approach is to have only the disk in a protective cartridge which is then loaded into the storage device. The problem is even more severe with optical media. Implementation in an optical system would require the interchange of an optical disk pack which would include all the necessary optical elements. Such would be prohibitably expensive.
One solution is the use of protective cartridges which only house the disk. The disk must then be loaded into the device for rotation by the permanently mounted device spindle. Protective cartridges which only contain the recording disk are well known for low density video and audio disks. Since information is recorded at a low density, such cartridges provide sufficient protection. However, more is needed to protect the surface of high density disks. While the presently developed cartridges can generally protect the disk from damage from exterior sources, the extremely sensitive nature of the recording surface can be damaged by contact with the interior surface of the disk cartridge itself. With low density audio and video recordings, this was not a particular problem. However, with the high density extremely sensitive recording surface of the magnetic and optical disks presently contemplated, contact between the recording disk surface and the interior walls of the cartridge itself can have a severe adverse impact on the performance of the disk.
What is needed then is a protective structure which not only contains the recording disk and protects that disk from exterior damage and contamination, but also protects the disk from being damaged as a result of contact with the interior surface of the protective structure itself.
It is an object of this invention to provide a means for preventing exterior damage to an information recording disk.
It is another object of the disclosed invention to provide a means for preventing contamination of the recording surface of an information recording disk.
It is yet another object of the disclosed invention to provide a means for preventing damage to the recording surface of an information recording disk while the disk is located in its protective cartridge.